1. Field of the Invention
The present invention relates to a horizontal machine tool in which a spindle head for horizontally supporting a rotatable tool spindle is guided on a first surface of a base, while a workpiece support is guided on a second surface of the base which surface is perpendicular to and adjacent to the first surface, as well as to a workpiece-support feed mechanism suitable for the horizontal machine tool. The present invention also relates an automatic tool change apparatus suitable for a horizontal machine tool having the above-described structure. The present invention further relates to a chip collection apparatus suitable for a horizontal machine tool having the above-described structure.
2. Description of the Related Art
As disclosed in Japanese Patent Application Laid-Open (kokai) No. 58-132432, in a horizontal machine tool of the above-described type, a spindle head that supports a horizontal tool spindle is guided on a first side surface of a column serving as a base to be movable in the axial direction of the tool spindle, while a workpiece support is guided on a second side surface of the column which is perpendicular to and adjacent to the first side surface in order to be movable in a vertical direction and a horizontal direction perpendicular to the tool spindle.
In another conventional machine tool disclosed in Japanese Utility Model Publication (kokoku) No. 2-26580, a spindle head that supports a horizontal tool spindle is guided on a top surface of a base such that the spindle head is movable in a direction parallel to the axis of the tool spindle as well as in a vertical direction perpendicular thereto, while a workpiece support that supports a workpiece at its upper end is guided on a front face of the base such that the workpiece support is movable in a horizontal direction perpendicular to the tool spindle.
In the former conventional machine tool, since the spindle head is guided on the first side surface in a cantilever fashion, a large difference in heat distribution is produced between that side surface and the opposite side surface, resulting in an inclination of the column. Further, since the workpiece support is guided in the vertical direction on the second side surface perpendicular to the first side surface, vertically extending guideways of the workpiece support incline by different amounts when the column inclines within a plane perpendicular to the tool spindle.
In the latter conventional machine tool, since the column is disposed on the base and the spindle head is guided in the vertical direction on the column, the overall machine height increases, which is disadvantageous for manufacture of a machine tool having a high rigidity. Further, since the workpiece support is guided on the vertical front face of the base such that the workpiece support is movable in a horizontal direction perpendicular to the tool spindle, a cover unit is horizontally disposed to extend in a direction perpendicular to a falling direction of chips in order to protect guideways for guiding the workpiece support from chips. Therefore, the cover unit hinders discharge of chips. In addition, there must be employed a telescopic cover unit or the like, which is not necessarily suitable for high speed feed of a movable member.
Meanwhile, in order to shorten tool exchange time, numerous improvements have been made in relation to automatic tool change apparatuses used in machine tools. For example, a cam mechanism as disclosed in Japanese Patent Application Laid-Open (kokai) No. 5-104377 has been employed as a drive mechanism for driving a tool change arm in order to produce advance/retraction motion and rotational motion of the tool change arm as a continuous motion to thereby increase the tool change speed.
Another approach for shortening tool change time is shortening a tool change arm in order to increase the speed of rotational motion of the tool change arm, as disclosed in Japanese Patent Application Laid-Open (kokai) No. 8-39381. In this conventional technique, the tool change arm is shortened through a decrease in the inter-axis distance between the tool spindle and a socket that holds a new tool when a tool change operation is performed. In the technique disclosed in the publication, in order to decrease the inter-axis distance between the tool spindle and the socket, an arm support shaft for supporting the tool change arm and an arm drive shaft which is rotated and axially moved by means of a cam-type drive mechanism and which transmits these motions to the arm support shaft are arranged to be parallel to each other and separated from each other in the vertical direction. Thus, a support section adapted to support the arm support shaft and positioned between the spindle head and a tool magazine during a tool change operation has a reduced width in a direction connecting the tool spindle and the magazine. The above-described structure enables a housing section that accommodates the arm drive shaft and the cam-type drive mechanism to have a width greater than that of the support section, as in conventional machine tools.
Further, a conventional automatic tool change apparatus is provided with a tool magazine which is disposed such that when a spindle head is returned to a tool change position defined at the rear side of the machine tool, the tool magazine is located adjacent to the spindle head. The tool magazine stores a plurality of tools such that the tools are directed to a direction parallel to or perpendicular to the tool spindle.
In the conventional tool change apparatus disclosed in Japanese Patent Application Laid-Open No. 8-39381, the relatively narrow support portion for supporting the arm support,shaft and the relatively wide drive section which accommodates the arm drive shaft and the cam-type drive mechanism must be separated from each other in the vertical direction. Therefore, the structure of the tool change arm unit becomes complex, and cost of manufacture increases.
Moreover, in a horizontal machine tool, a chip collection apparatus utilizing a chip conveyor has been conventionally used.
As disclosed in, for example, Japanese Patent Application Laid-Open (kokai) No. 6-247523, such a chip collection apparatus is constructed such that a chip inlet for collecting chips is formed in a bed on which a machine tool table and a main spindle are placed, and a chip conveyor is disposed under the chip inlet.
The chip conveyer has an endless chain that is wound around a pair of sprockets. The endless chain is caused to travel by means of a motor attached to one of the sprockets, so that chips falling down from the chip inlet are discharged to a chip collection box disposed behind the bed.
However, the chip collection apparatus utilizing a chip conveyor requires a large number of parts such as an endless chain and sprockets. Further, such a chip collection apparatus is built in the bed or disposed under the bed for use, the height of the bed increases, and maintenance and management of the chip collection apparatus are difficult.